This research will focus on a series of respiratory features (markers) which may be predictive of mild lung disease. The objective is to assess whether the markers may be useful as early indicators of health effects in epidemiologic studies of low level environmental exposures. The research plan is divided into four categories according to the type of marker and the underlying condition for which it may be predictive: (1) the performance of an unacceptable lung function test (failure) as a marker for respiratory symptoms or early clinical disease; (2) pulmonary function test failure as a marker for pre-clinical disease; (3) pleural plaques as a marker for risk of asbestos related cancer; and (4) large drop in FEV1 over the workshift as a marker for early lung disease in cotton textile workers. Data from several large cohort studies, e.g., Harvard's Six Cities and UCLA's CORD data, are available to the applicant. Guidelines for standardizing pulmonary function testing in epidemiologic studies were proposed in 1978 which recommended excluding nonreproducible measurements from data analysis. We will continue to examine whether this practice results in the exclusion of data from subjects with mild disease and may therefore result in selection bias, particularly in studies of low exposures. Statistical methods will be developed based on longitudinal data for estimating the ventilatory function of subjects with nonrepeatable tests. The precise magnitude of the cancer risk associated with low exposure asbestos in public schools is difficult to estimate directly. Pleural plaques, however, are a more common effect of exposure and may be used as a measure of lung dose and thus as an indirect measure of cancer risk. The prevalence of plaques will be estimated in a cohort of custodians and teachers from Boston public schools. A follow-up study of a cohort of Chinese textile workers first studied in 1981 is described. The associations between drop in FEV1 over the workshift and annual rate of FEV1 decline and development of byssinosis will be estimated. Dose-response estimates will also be made for the relationships between past and current dust levels and acute and chronic health effects.